Pick-up cartridge with improved oscillating system

ABSTRACT

The oscillating system of a pick-up cartridge is formed primarily by a tubular cantilever member which is slit longitudinally and in one form receives an inserted magnetic armature at the end of the tubular member which is fixed while the free end carries holes on opposite sides, one of which intersects the longitudinal slit and which hole is smaller in diameter than the diameter of the hole on the opposite side with the transducer needle forcibly projecting through the aligned holes.

United States Patent Sakai Sept. 30, 1975 1 PICK-UP CARTRIDGE WITH IMPROVED 1531.067 11 1950 Massa 274/38 OSCILLATING SYSTEM 3 694,586 9/1972 Grado 274/37 X [75] Inventor: Yasunori Sakai, Tokorozawa, Japan Primary Erammer-Rxchard E. Aegerter l Asslgneei Pioneer Electronic Corporation, Assistant Examiner-Charles E. Phillips Tokyo, Japan Attorney, Agent, or FirmSughrue, Rothwell, Mion,

22 Filed: July 15, 1974 Macpeak Appl. No.: 488,864

[ 5 7 1 ABSTRACT The oscillating system of a pick-up cartridge is formed primarily by a tubular cantilever member which is slit longitudinally and in one form receives an inserted magnetic armature at the end of the tubular member which is fixed while the free end carries holes on opposite sides, one of which intersects the longitudinal slit and which hole is smaller in diameter than the diameter of the hole on the opposite side with the transducer needle forcibly projecting through the aligned holes,

5 Claims, 6 Drawing Figures US. Patent Sept. 30,1975 3,909,008

HUI PRIOR ART H02 PRIOR ART 3 2 I 5 /,/4 3 k w A n s PICK-UP CARTRIDGE WITH IMPROVED; OSCILLATING SYSTEM BACKGROUND OF THE INVENTION' 1. Field of the Invention This invention relates to pick-up catridges for reproducing sound from sound record discs and more particularly to an improved oscillation system of the cantilever type.

2. Description of the Prior Art One example of a conventional oscillation system for a pick-up cartridge (hereinafter referred to as a cartridge) of the electromagnetic type is shown in FIG. I. In this type of cartridge, a needle 2 is secured to the free end of a tubular cantilever member I, and an armature 3 consisting of a permanent magnet or a high permeable magnetic material is secured by being tele scoped within the other end of the cantilever member 1. In order to secure the needle 2 to the tubular cantilever member 1, holes having diameters substantially equal to the diameter of the needle 2 are formed within the free end of the tubular cantilever member 1, for instance, by punching, Preferably, the tubular member 1 which is essentially cylindrical in form, is flattened at one end so as to take an oval cross section at the point where it receives the needle 2. However, if the diameters of the holes are slightly smaller than that of the needle 2 which is inserted therein, cracks may be caused within the cantilever member 1 during forcible insertion of the needle 2, thus making it impossible to hold the needle 2 rigidly to the cantilever member 1 during operation. This causes the drawback in that the needle 2 may be easily dropped out of the cantilever member 1 when undue forces are applied to the needle 2 or the cartridge during sound reproduction from the sound record disc. On the other hand, if the diameter of the hole is slightly larger than that of the needle 2, the needle 2 tends to be inclined rightwardly or leftwardly relative to a line perpendicular to the sound re cording disc so that the reproducing quality, that is, the channel balance, is effected, the tracing characteristics are deteriorated and some reproduction occurs with distortion.

Further, in the above described conventional cartridge oscillation system, the fixing of the needle 2 to the cantilever member 1 is achieved mostly through the use of an adhesive agent and hence the needle 2 cannot be secured to the cantilever member with sufficient strength.

In addition, if the outer diameter of the armature 3 which is fixed by force insertion to the other end of the cantilever I, is slightly greater than the inner diameter of the tubular cantilever member 1, it is impossible to insert the armature 3 into the tubular cantilever member I, and if it is forced, during insertion the cantilever tubular member 1 may be cracked or bent, thus making it very difficult to assemble these two members.

Conversely, if the inner diameter of the tubular cantilever member 1 is greater than the outer diameter of the armature 3, the play which exists therebetween tends to create misalignment of both members in terms of their longitudinal axes, thus deteriorating the channel balance and channel separation of the cartridge and causing trace distortion in sound output.

Another example of the conventional electromagnetic type cartridge is shown in FIG. 2. In this example, the tubular cantilever member 1 and the armature 3 are connected by way of a sleeve 5, that is, both tubular cantilever member 1 and the armature 3 are inserted within the sleeve 5 from opposite ends and are supported by means of an elastic member 4 in similar fashion to the elastic member 4 of the prior art device of FIG. I. In this prior art arrangement, if the outer diameter of cantilever 1 is slightly greater than the inner diameter of sleeve 5, the tubular cantilever member 1 cannot be inserted into sleeve 5. When the cantilever member 1 is forced into the latter, bending of the cantilever member 1 or cracking of the sleeve 5 will result. If the outer diameter of the cantilever member 1 is smaller than the inner diameter of sleeve 5, the play between the two members may cause misalignment between the longitudinal axis of the cantilever member and that of the sleeve, and the resultant obliquely connected cantilever member and sleeve will deteriorate the channel balance and channel separation of the cartridge, thus causing trace distortion. In similar fashion to the aforementioned example. the fixing of the canti lever member and the sleeve in this case depends mostly on the use of an adhesive agent, Thus, the strength of the connected portion of these elements is insufficient and the application of any undue force to the tip of the needle during the reproduction of sound from the phonograph record may cause the cantilever member to drop out or to rotate with respect to the sleeve which supports the same.

The above drawbacks of such conventional construction for the oscillation system of a pick-up catridge may be overcome through the use of the present invention. Thus, a primary object of the present invention is to provide a cantilever member which, when the needle is forced into the cantilever member, does not result in cracking of that member and permits the needle to be secured rigidly to the cantilever member without the aid of an adhesive agent.

Another object of the present invention is to provide a cantilever member which can securely mount the needle without play between the needle and that member and without any possibility of oblique alignment of the needle to either the right or the left and whereby the deterioration of the various qualities such as channel balance, channel separation and trace distortion may be substantially eliminated.

A still further object of the present invention is to provide a cantilever member for an oscillation system which, after the needle is forced therein, holds the needle by resilient action so that the needle is securely mounted within the cantilever member and which results in substantially eliminating the possibility of the needle dropping out of the cantilever member by any undue handling thereof at the time of sound reproduction.

A further object of the present invention is to provide a cantilever member for the oscillation system of a pick-up cartridge in which the armature can be inserted and secured easily without causing any play or oblique disposition of this member relative to the armature.

An additional object of the invention is to provide a cantilever member for an oscillation system for a pickup cartridge which can be easily connected to a sleeve without causing any play or misalignment therebetween and wherein the connection is firm and rigid therebetween. V

SUMMARY OF THE INVENTION The invention resides in a pickup cartridge oscillation system of improved construction, wherein a cantilever member supports at its outboard or free end a transducing needle, and the improvement resides in the cantilever member comprising a hollow, tubular member including a longitudinal slit extending inwardly from the free end thereof at least partially the length of the tubular member and having opposed aligned holes within the tubular member adjacent the free end. The transducing needle is force fitted into the aligned hole with the longitudinal slit intersecting one of the holes, which hole has a diameter less than that of the other hole. The tubular member may be flattened in oval shape at its free end with the holes passing therethrough being aligned with the minor axis of the oval shaped flattened end. The tip of the needle may be proximate the larger diameter hole through which it passes.

The magnetic armature may comprise a cylindrical rod having a diameter on the order of the inner diameter of the tubular cantilever member and insertably received within the end of that cantilever member opposite that carrying the needle. Alternatively, the fixed end of the tubular cantilever member may carry the longitudinal slit and it may be insertably received within a sleeve having an internal diameter approximating the outside diameter of the tubular cantilever member with a rod-like magnetic armature being insertably received within the opposite end of the sleeve and in end abutment with the inserted end of the tubular cantilever member.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a profile view, partially in section of an oscillation system of a conventional sound pick-up cartridge.

FIG. 2 is a profile view, partially in section, of another example of the oscillation system of a conventional sound pick-up cartridge.

FIG. 3 is a profile view, partially in section, of an electromagnetic type sound pick-up cartridge having one form of the oscillation system of the present invention.

FIG. 4 is a profile view, partially in section, of yet another form of the oscillation system for an electromagnetic type sound pick-up cartridge employing the present invention.

FIG. 5 is a profile view, partially in section, of yet another example of an electromagnetic type sound pickup cartridge employing the oscillation system of the present invention in modified form.

FIG. 6 is a cross sectional view of the cantilever member of the several embodiments of the present invention showing the manner of securing the needle at the free end of the tubular cantilever member.

DESCRIPTION OF PREFERRED EMBODIMENTS A preferred example of the present invention as applied to an oscillation system of an electromagnetic type cartridge is illustrated in FIG. 3. In this figure, a tubular cantilever member 1 has a needle 2 secured at the free or outboard end of the cantilever member 1, the member being provided with a longitudinal slit 11 which extends the length of the same. In like manner to the prior art devices of FIGS. 1 and 2, the end of the member 1 carrying the needle 2 is flattened into oval cross section in contrast to the circular configuration of the major length of the cantilever member 1. An armature 3 formed for instance of a material having high magnetic permeability or constituting a permanent magnet which is essentially in the form of the rod or solid cylinder, is fixed to the end of the tubular cantilever member 1 opposite that carrying the needle 2. The rod-like armature 3 is insertably received within the tubular cantilever member 1 having a diameter essentially equal to the internal diameter of that member. An elastic supporting member 4 made of rubber or plastic to provide damping and being provided with a central hole receives by way ofa tight fit, the end of the tubular cantilever member 1 housing the armature 3. The preferred manner in which the needle 2 is carried by the tubular cantilever member I may be seen by reference to FIG. 6, both for the embodiment of FIG. 3 as well as the embodiments of FIGS. 4 and 5. Reference to FIG. 6 illustrates in section the hollow tubular cantilever member 1 as having a slit 11 and being provided with opposed aligned holes 13 and 14 within the flattened or oval shaped portion thereof, hole 13 being of a diameter in excess of hole 14 as evidenced by the dimensional illustrations I1 and I1 respectively. In the illustration of FIG. 6, the needle 2 has yet to penetrate the aligned holes 13 and 14 of the tubular cantilever member 1. However, by the dotted line indication of that needle 2, it may be seen that the diameter of the needle approximates the diameter I1 of hole 13 and the diameter is in excess of the diameter 11 of hole 14. Thus, during insertion, necessarily the tubular cantilever member I must have the longitudinal slit ll dislocation widened so as to permit entry of the needle 2 during the force fit of the needle 2 to the cantilever member 1. Thus, according to the present invention, in all embodiments, the longitudinal slit 11 is provided along the length of the cantilever member 1, at least a portion of the distance inwardly from that end supporting the needle 2 although preferably the complete length of the same, furthermore, the diameter 11, of the hole 14 for receiving the needle on the side of the cantilever member 1 having the slit which intersects the same, is made slightly smaller than the diameter 12 of the hole on the opposite side thereof so that the needle 2 can be far more rigidly fixed to the cantilever member l. The slit 11 further facilitates the coupling between the armature 3 and the cantilever member 1 or the cantilever member 1 to the sleeve 5 in the embodiment of FIG. 4. The cantilever member 1 is preferably made by rolling a metal sheet into tubular form and leaving a gap at the abutting end forming slit II. The present invention is particularly effective when the cantilever member 1 is made of material such as beryllim which can be drawn or shaped only with difficulty because of its low ductility.

Reference to FIG. 4 shows in longitudinal section another example of the oscillation system of a sound pickup cartridge of the present invention, this cartridge also being of the electromagnetic type wherein a sleeve 5 connects tubular cantilever member I having a longitudinal slit 11 extending the length of the same with a rod-like armature 3 which is formed of a permanent magnet or constitutes a material having high magnetic permeability. The diameter of said rod-like armature is generally slightly less than the outside diameter of said tubular cantilever member and said sleeve has an internal diameter equal to that of said armature and slightly less than the outside diameter of said tubular cantilever member. Again, an elastic support member 4 for providing damping action to the oscillating cantilever member 1, at its center, is provided with an axial hole which tightly receives sleeve 5. In this embodiment, the tubular member 11 may be compressed slightly, closing the gap defined by slit 11 at the point where the inboard end ofthe cantilever member 1 is inserted within the sleeve 5, which end terminates in abutting contact with armature 3.

Referring next to FIG. 5, this figure illustrates a longitudinal sectional view of still another example of an electromagnetic type sound pick-up cartridge employing the oscillation system of the present invention. A supporting wire 6 made of a metal or plastic carries an auxiliary pipe or sleeve 7 which interconnects the supporting wire 6 to the larger diameter. tubular cantilever member 1. In this embodiment, armature Sis in the form of an annular coil which surrounds the cantilever member 1 or alternatively it may constitute an annular permanent magnet or an annular element of a material having high magnetic permeability. An elastic member 9 in annular form surrounds the supporting wire 6 andv is disposed intermediate of holder 10 which fixedly locates and supports the wire 6 and acts as backing for the elastic member 9. The elastic member may be formed of rubber or plastic and acts to principally damp the action of the oscillation system. Preferably, the holder 10 includes a cylindrical projecting portion which is partially inserted into the central hole of the elastic member 9 along with a cylindrical member which facilitates the support of the armature in contact with the elastic member 9 on the side opposite of that member from holder 10. Member 15 is of hollow T- shape in cross section to receive wire 6 and to provide outer diameter portions equal respectively to the diameter of the hole within the center of the elastic member 9 and the hole within the center of the armature 8.

The present invention in all its form has the following advantageous features. First, since the diameters of the holes for receiving the needle within the cantilever member differ slightly in terms of the holes within the upper and lower sides thereof, and the slit 11 is provided along the length of the cantilever member. The insertion of the needle into the hole is far more easily facilitated than in conventional cases, and because the portion of the cantilever member along the slit has the ability to restore itself to the original state by its natural resiliency, the needle can be firmly secured to the cantilever member without causing play or cracking or offsetting the needle from its correct position, that is, preventing it from being inclined to the left or to the right from a perpendicular position when looking along the axis of the oval portion of the cantilever member. As a result of the rigid securing of the needle to the cantilever member, in the correct manner, the channel balance and channel separation are not deteriorated and the reproduction of the recorded sound from the disc will be facilitated without trace distortion. Secondly, since the needle is held firmly in its position by the resilient force of the cantilever member tending to restore itself to its original state when displaced by insertion of the needle, there is no possibility of the needle being dropped out of the cantilever member, even if the needle is handled rather roughly during the second reproduction activity with respect to the record disc.

Thirdly, since the cantilever is provided with a selfrestoring ability as described above, the precision required for forming the holes for receiving the needle are far less critical and advantageous features such as cost reduction and improved adaptability to mass produce needles and tubular cantilevers is thereby obtained. Fourthly, since the longitudinal slit is provided within the cantilever, and where that slit extends the complete length of the cantilever member, the armature may be easily inserted into the cantilever or the cantilever member inserted within a sleeve without causing play therebetween. Thus, the armature can be firmly secured to the cantilever member in a rigid manner without causing any misalignment with respect to their axes, whereby any deterioration of the output characteristics such as channel balance and channel separation and any trace distortion is substantially eliminated and the reproduction of recorded sound of high quality is thereby obtained. Fifthly, since the cantilever member can be firmly secured to the sleeve without play or misalignment between the axis, characteristics such as channel balance, channel separation, tracking distortion or vertical tracking distortion can be improved, thus enabling the acquisition of good sound reproduction from the recorded disc, and furthermore, any possibility of the cantilever member being dropped off the sleeve or rotated relative to the sleeve in that embodiment of the invention, can be substantially eliminated. As a sixth feature, an auxiliary pipe or tube may be firmly secured to the cantilever member, and a supporting wire may in turn be firmly secured to the auxiliary pipe or tube by being received therein with excellent alignment of the respective axes of these members so that the above described characteristics may be improved and reproduction of sound from the record disc with high quality may be thereby realized. As a seventh feature, the armature can be easily inserted into the cantilever member without play with good alingment between their axes with the sound characteristic improved and excellent reproduction of sound obtained thereby.

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is: 1. In a pick-up cartridge oscillation system including a tubular cantilever member having a relatively fixed end and a relatively free end and supporting at its free end, a sound transducing needle, the improvement wherein:

said cantilever member comprises a hollow tubular member including a longitudinal slit extending inwardly from said free end at least partially the length of the tubular member and having opposed, aligned holes within said tubular member adjacent the free end, with said longitudinal slit intersecting one of said holes, 7

said transducing needle having a diameter approximately equal to the diameter of said hole opposite that being intersected by said longitudinal slit,

said hole having said longitudinal slit intersection being of a diameter less than that of said needle,

and wherein, said transducing needle is force fit into said aligned holes and projects from one side of said tubular cantilever member.

2. The pick-up cartridge oscillation system as claimed in claim 1, wherein said tubular cantilever member is flattened into oval shape and said holes are aligned with the minor axis thereof and wherein the tip of said needle is proximate the larger diameter hole receiving the same.

3. The pick-up cartridge oscillation system as claimed in claim 1, wherein said longitudinal slit extends the length of said tubular cantilever member and said system further includes a rod-like armature of a diameter slightly in excess to the internal diameter of said tubular cantilever member and being telescopingly received within the end of that member opposite that holding said needle.

4. The pick-up cartridge oscillation system as claimed in claim 1, wherein said longitudinal slit extends the length of said tubular cantilever member, said system further comprising a rodlike armature of a diameter generally slightly less than the outside diameter of said tubular cantilever member and said system further includes a sleeve having an internal diameter equal to that of said armature and being slightly less than that of the outside diameter of said tubular cantilever memher, and wherein the end of said tubular cantilever member not carrying said needle is inserted within one end of said sleeve, and said armature is inserted within the other end of said sleeve with the ends of said armature and said tubular cantilever member within said sleeve in abutting contact with each other.

5. The pick-up cartridge oscillation system as claimed in claim 1, further comprising: a fixed holder including a cylindrical projecting portion, a wire fixed to said holder and projecting through the center of said cylindrical projection portion, and extending axially beyond the end of the same. said longitudinal slit within said hollow tubular cantilever member extending the full length of the same, the end of said hollow tubular cantilever member not carrying said needle receiving the projecting end of said wire, a tubular member having an outer diameter slightly in excess of the internal diameterof said cantilever member telescopingly receiving the projecting end of said wire and in turn being received within the end of said cantilever member remote from said needle under a force fit, an annular armature surrounding the end of said cantilever member remote from said needle and an elastic damping member interposed between said holder and said armature and being supported by said holder projection. 

1. In a pick-up cartridge oscillation system including a tubular cantilever member having a relatively fixed end and a relatively free end and supporting at its free end, a sound transducing needle, the improvement wherein: said cantilever member comprises a hollow tubular member including a longitudinal slit extending inwardly from said free end at least partially the length of the tubular member and having opposed, aligned holes within said tubular member adjacent the free end, with said longitudinal slit intersecting one of said holes, said transducing needle having a diameter approximately equal to the diameter of said hole opposite that being intersected by said longitudinal slit, said hole having said longitudinal slit intersection being of a diameter less than that of said needle, and wherein, said transducing needle is force fit into said aligned holes and projects from one side of said tubular cantilever member.
 2. The pick-up cartridge oscillation system as claimed in claim 1, wherein said tubular cantilever member is flattened into oval shape and said holes are aligned with the minor axis thereof, and wherein the tip of said needle is proximate the larger diameter hole receiving the same.
 3. The pick-up cartridge oscillation system as claimed in claim 1, wherein said longitudinal slit extends the length of said tubular cantilever member and said system further includes a rod-like armature of a diameter slightly in excess to the internal diameter of said tubular cantilever member and being telescopingly received within the end of that member opposite that holding said needle.
 4. The pick-up cartridge oscillation system as claimed in claim 1, wherein said longitudinal slit extends the length of said tubular cantilever member, said system further comprising a rod-like armature of a diameter generally slightly less than the outside diameter of said tubular cantilever member and said system further includes a sleeve having an internal diameter equal to that of said armature and being slightly less than that of the outside diameter of said tubular cantilever member, and wherein the end of said tubular cantilever member not carrying said needle is inserted within one end of said sleeve, and said armature is inserted within the other end of said sleeve with the ends of said armature and said tubular cantilever member within said sleeve in abutting contact with each other.
 5. The pick-up cartridge oscillation system as claimed in claim 1, further comprising: a fixed holder including a cylindrical projecting portion, a wire fixed to said holder and projecting through the center of said cylindrical projection portion, and extending axially beyond the end of the same, said longitudinal slit within said hollow tubular cantilever member extending the full length of the same, the end of said hollow tubular cantilever member not carrying said needle receiving the projecting end of said wire, a tubular member having an outer diameter slightly in excess of the internal diameter of said cantilever member telescopingly receiving the projecting end of said wire and in turn being received within the end of said cantilever member remote from said needle under a force fit, an annular armature surrounding the end of said cantilever member remote from said needle and an elastic damping member interposed between said holder and said armature, and being supported by said holder projection. 